The present invention relates to medical methods and apparatus, and more specifically to a method and an apparatus for determining the heat and cold sensation and pain thresholds of the human nerve system.
Determining the temperature level at which a subject begins to feel a sensation or pain due to the application of a thermal (heat or cold) stimulus is becoming increasingly important for establishing the status of the so-called small or unmyelinated nerve fibres which comprise about 85% of all nerve fibres in the peripheral nerve system, and of various other body functions. For instance, it has been shown that the temperature sensitivity of a patient suffering on diabetes mellitus type I varies synchronously with the blood sugar level.
F. Strian et al describe in the West-German medical magazine "Der Nervenarzt", 1984, 55: 103-107 a method of determining the temperature sensation threshold by applying heat of controllable temperature by means of a heat applicator in the form of a Marstock thermode, which comprises a Peltier element. The temperature of the applied heat is progressively increased until the subject under investigation signals that he or she feels a heat sensation or pain, which he or she signals by pressing a button. This terminates the application of heat. A cold sensation or pain threshold may be determined by a similar procedure. Several threshold values obtained as described are averaged.